Guide for roller cam follower

Abstract

A guide (28) is provided for retrofitting an existing internal combustion engine block (10) with roller cam followers (24 and 26) in place of conventional barrel-type lifters, without modification of the block itself. The guide includes a guide bar (64), keyed to the upper body (38) of each follower to allow limited rotational freedom thereof and a resilient C-shaped spring clip (70) which simultaneously bears downwardly on the upper surface of the guide bar and upwardly on the lower surface (40) of an engine block boss (18) defining follower receiving bores (20 and 22). Annular spacers (72) are provided, if required, to displace the guide bar upwardly from the upper surface (52) of the boss. An upper leg (76) of the spring clip wraps around the guide bar for retention therewith and a lower leg (78) of the spring clip is necked at a point (86) intermediate adjacent cylindrical portions (30 and 32) of the follower boss for retention therebetween.

We claim: 
     
       1. In an internal combustion engine of the type including a valve train incorporating at least one roller cam follower and a block defining a boss characterized by an upper surface, a lower surface and a bore for slidably receiving said follower, follower guide means comprising: a member defining keying surfaces nominally spaced from said follower at a point adjacent said upper surface and operative to effect limited non-contacting rotational freedom of said follower within said bore; and   means for resiliently connecting said member to said boss by embracingly engaging said member and said lower surface.   
     
     
       2. The follower guide means of claim 1, wherein said resilient connecting means comprises a generally C-shaped spring clip including an upper leg bearing downwardly against said member and a lower leg bearing upwardly against said lower surface. 
     
     
       3. The follower guide means of claim 2, wherein said spring clip is constructed of metal band stock. 
     
     
       4. The follower guide means of claim 1, wherein said member is operative to limit rotational freedom of said follower to a predetermined range. 
     
     
       5. The follower guide means of claim 4, wherein said predetermined range comprises approximately ±3 degrees about a nominal center. 
     
     
       6. The follower guide means of claim 2, wherein said resilient connecting means further comprises means for mechanically interconnecting said upper leg with said member. 
     
     
       7. The follower guide means of claim 6, wherein said interconnecting means comprises means depending from the free end of said upper leg and at least partially circumferentially embracing said member. 
     
     
       8. The follower guide means of claim 2, wherein said resilient connecting means further comprises means for mechanically interconnecting said lower leg with said boss. 
     
     
       9. The follower guide means of claim 1, further comprising means operative to rigidly space said member a predetermined distance above said top surface. 
     
     
       10. In an internal combustion engine of the type including a valve train incorporating at least two roller cam followers and a block defining a boss characterized by an upper surface, a lower surface and a bore for slidably receiving each said follower, follower guide means comprising: a member extending between said followers at point adjacent said upper surface and defining keying surfaces nominally spaced from said followers for limiting non-contacting rotational freedom thereof within said bores; and   means for resiliently connecting said member to said boss by embracingly engaging said member and said lower surface.   
     
     
       11. The follower guide means of claim 10, wherein said resilient connecting means comprises a generally C-shaped spring clip including an upper leg bearing downwardly against said member and a lower leg bearing upwardly against said lower surface. 
     
     
       12. The follower guide means of claim 11, wherein said spring clip is constructed of metal band stock. 
     
     
       13. The follower guide means of claim 10, wherein said member is operative to limit rotational freedom of said followers to a predetermined range. 
     
     
       14. The follower guide means of claim 13, wherein said predetermined range comprises approximately ±3 degrees about a nominal center. 
     
     
       15. The follower guide means of claim 11, wherein said resilient connecting means further comprises means for mechanically interconnecting said upper leg with said member. 
     
     
       16. The follower guide means of claim 15, wherein said interconnecting means comprises means depending from the free end of said upper leg and at least partially circumferentially embracing said member. 
     
     
       17. The follower guide means of claim 15, wherein said resilient connecting means further comprises means for mechanically interconnecting said lower leg with said boss. 
     
     
       18. The follower guide means of claim 17, wherein said boss comprises two generally parallel cylindrical portions defining said bores and interspaced a predetermined distance by a web defining said lower surface, said lower leg being characterized by an intermediate area of reduced width disposed between said cylindrical portions and in an abutting relationship therewith. 
     
     
       19. The follower guide means of claim 18, wherein said cylindrical portion have a minimum spacing S, said lower leg has a nominal width N and said intermediate area of reduced width is of a dimension W, and wherein said minimum spacing, nominal width and dimension conform to the relationship: N>S>W. 
     
     
       20. The following guide means of claim 10, further comprising means operative to rigidally space said member a fixed predetermined distance above said top surfaces. 
     
     
       21. The follower guide means of claim 20, wherein said spacing means comprises an annular ring disposed substantially coaxially with each side bore and having a characteristic inner diameter dimensionally not less than that of said bore associated therewith. 
     
     
       22. In a multi-cylinder internal combustion engine of the type including a valve train incorporating a pair of roller cam followers associated with each said cylinder and a block defining a integral boss for each said cylinder, each said boss defining an upper surface, a lower surface and bores for slidingly receiving said associated pair, follower guide means comprising: an elongated member defining keying surfaces nominally spaced from each said follower at points adjacent each said respective upper surface and operative to effect limited non-contacting rotational freedom to each said follower within each associated bore; and   at least one means for resiliently connecting said member to one said boss by embracingly engaging said member and said associated boss lower surface.   
     
     
       23. The follower guide means of claim 22, wherein said resilient connecting means comprises at least two generally C-shaped spring clips.